Fatigue behavior and fracture mechanism of al alloy 7075-t6 under ultrasonic cycling deformation

Qiang Chen, N. Kawagoishi, G. Hashiguchi, M. Oki, K. Kusukawa

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

To investigate the effects of loading frequency on fatigue crack growth behavior, ultrasonic fatigue tests were carried out for an extruded age-hardened Al alloy 7075-T6 in ambient air and in N2 gas. The results obtained were compared with those in rotating bending fatigue. Fatigue strength was higher in ultrasonic fatigue than in rotating bending fatigue. This may be caused by the retardation of crack initiation and early crack propagation. In ultrasonic fatigue, the growth direction of cracks changed macroscopically from tensile mode to shear mode with the direction oblique about 35 degrees to the stress axis. Fracture mechanism involved changed from striations featured to transgranular facets and microvoids predominated. Crack growth rate at growth mode transition was ~3x10-9 m/cycle. The relation between applied stress, a, and crack depth, bT, at the transition sites can be approximated as anbT = constant. The results were discussed from viewpoints of crack tip plasticity, time dependent environment effect and the texture microstructure of the alloy.

Original languageEnglish
Title of host publication17th European Conference on Fracture 2008: Multilevel Approach to Fracture of Materials, Components and Structures
Pages2622-2629
Number of pages8
Volume3
Publication statusPublished - 2008
Externally publishedYes
Event17th European Conference on Fracture 2008: Multilevel Approach to Fracture of Materials, Components and Structures, ECF17 - Brno, Czech Republic
Duration: Sep 2 2008Sep 5 2008

Other

Other17th European Conference on Fracture 2008: Multilevel Approach to Fracture of Materials, Components and Structures, ECF17
CountryCzech Republic
CityBrno
Period9/2/089/5/08

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All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering

Cite this

Chen, Q., Kawagoishi, N., Hashiguchi, G., Oki, M., & Kusukawa, K. (2008). Fatigue behavior and fracture mechanism of al alloy 7075-t6 under ultrasonic cycling deformation. In 17th European Conference on Fracture 2008: Multilevel Approach to Fracture of Materials, Components and Structures (Vol. 3, pp. 2622-2629)